1. Field of the Invention
This invention relates to a stormwater pretreatment system, more particularly to a stormwater pretreatment system that uses an actuated valve to isolate the disposal well from the stormwater in the event the stormwater is contaminated by gasoline, diesel fuel, kerosene or other hydrocarbons. Further, this invention relates to a stormwater pretreatment system that isolates standing water in the oil/water separation to reduce the effect of infestation of mosquito larvae.
2. Prior Art
When it rains on unimproved natural land, the rain and stormwater runoff is either absorbed into the soil or moves along the surface of the land, moving downward towards creeks and larger and larger rivers. However, as areas become more densely populated, this natural dispersion of rain and stormwater is altered by the man-made improvements such as parking lots, roads and buildings and earth work disturbing the original contours of the land. This also leaves less open ground surface to absorb the rain, thus adding to the stormwater runoff.
In many cities, stormwater sewers are constructed to handle the large amount of stormwater runoff that comes off of the buildings, parking lots and roads. The stormwater sewers route the water to creeks and drainage ditches which form the tributaries to larger rivers. However, most cities in arid regions do not have a stormwater sewer; therefore, when it rains there is no pathway for disposing of the stormwater runoff coming from the buildings, parking lots, roadways, etc.
In many of the cities without stormwater sewers, landowners are required to construct a system to collect the stormwater runoff and a disposal well or dry well which puts the water into a pervious subsurface structure.
The disposal of the stormwater can be further complicated when it becomes contaminated with petroleum byproducts or other substances which can contaminate the groundwater or aquifer. As such, it is necessary to have a system which is capable of stopping the flow of stormwater runoff into the dry well when gasoline, diesel fuel, kerosene or other hydrocarbons are present in the stormwater runoff.
Catch basins capable of intercepting contaminated stormwater runoff are known in the art. U.S. Pat. No. 5,569,372 entitled “Catch Basin Structure for Interception of Contaminants Having Detachable Parts” issued on Oct. 29, 1996 discloses a catch basin structure equipped with a manual valve capable of stopping the flow of stormwater runoff. Likewise, U.S. Pat. No. 5,067,850 entitled “Apparatus for Detection and Containment of Pollution in a Drainage System” issued to Robert L. Gray on Nov. 26, 1991 discloses a storm drainage system including a gate which controls the release of the contents of the drainage system. The gate is motor activated which is responsive to manual activation or hydrocarbon sensor activation.
U.S. Pat. No. 5,160,036 entitled “Automatic Pollution Containment and Alert Apparatus for Liquid Drainages” issued to Charles P. Childers on Nov. 3, 1992 discloses an apparatus for containing liquids and pollution within a liquid drainage comprising a first conduit, a second conduit, a liquid barrier, a means for lifting, and a means for sensing pollution. In the device disclosed in the Childers' patent, the one end of the second conduit can be lifted to stop the flow of the drainage.
While the Smith, Gray and Childers patents all disclose ways of stopping the flow of stormwater runoff in the event of contamination, they do not disclose a complete system necessary for collecting, pretreating and disposing of stormwater runoff into the groundwater or an aquifer.
The ENVIBRO System marketed by McGuckin Drilling, Inc. is a system to pretreat stormwater runoff and dispose of it into the groundwater or an aquifer. The ENVIBRO System, as disclosed in the brochure, has a collection chamber which feeds into a three-chambered separator which removes silt and other impurities from the stormwater. The three-chambered separator feeds into a dry well which disposes of the stormwater into the groundwater or an aquifer. The ENVIBRO System has a passageway between the three-chambered separator and the disposal well. The entry into this passageway is partially filled with a plurality of proprietary IMBIBER beads.
Under normal operation, water passes freely through the entryway. However, when contacted by an active organic liquid, the IMBIBER beads absorb the liquid and expand. The swollen beads fill the entry into the passageway, thus stopping the flow of contaminated water. Once the system has been activated by a pollutant, the flow of water stops. In order to reuse the system, the polluted water must be pumped off and the entryway with the beads must be replaced. This adds additional cost to the operation and requires additional time.